Hot-gas reciprocating engines of the displacer piston type



Feb, 7, 196? R. J. MEYER ETAL HOT-GAS RECIIROCATING ENGINES OF THEDISPLACER PISTON TYPE Filed June 24, 1965 6 Sheets-Sheet 1 INVENTOR3Feb. 7, 1967 R. J. MEYER ETAL. 3,302,393

HOT-GAS RECIPROCATING ENGINES OF THE DISPLACER PISTON TYPE Filed June24, 1965 6 Sheets-Sheet 2 HOT GAS RESCIPHOCATING ENGINES OF THE DISPLAf5 Sheets-$heet C5 Filed June 13 k H INVENTORJLFI Feb 7, 1.967 R. J.MEYER ETAL.

HOT-GAS RECIPROCATING ENGINES OF THE DI5PLAGER PISTON TYPE Filed June24, 1965 6 Sheets-Sheet 4 INVENTORS 7, 1967 IR. J- MEYER ETAL.

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HOT-GAS REGIPROCATING ENGINES OF THE DISPLACBR PISTON TYPE Filed June24, 1965 6 Sheets-Sheet 5 INVENTORJ ROELF J. MEYER ALBERT A. DROS AUGUSTA. LIEBE Nm 6? O2 3 HOT-GAS RECIPROCATING ENGINES OF THE DISPLACERPISTON TYPE Filed June 24, 1965 6 Sheets-Sheet 6 INVENTOR; ROELF J.MEYER ALBERT A. OROS AUGUST 4. LIEBE United States Patent 3,302,393HOT-GAS RECIPROCATING ENGINES OF THE DISPLACER PISTON TYPE Roelf JanMeyer, Albert August Dros, and August Albert Liebe, all of Emassingel,Eindhoven, Netherlands, assignors to North American Philips Company,Inc., New York, N.Y., a corporation of Delaware Filed June 24, 1965,Ser. No. 466,860 Claims priority, application Netherlands, June 23,1964, 64/06751; July 22, 1964, 64/08345 11 Claims. (Cl. 6024) Theinvention relates to a thermodynamic reciprocating engine of thedisplacer-piston type, comprising at least one pair of identical crankseach located on one side of a plane going through the center line of theengine and forming part of two crank shafts which rotate in synchronismin co-phase and in relatively opposite directions. The center lines ofthe shafts are parallel to each other and are located symmetrically oneon each side of the plane going through the center line of the engine ina plane at right angles to said center line. Each pair of associatedcranks is connected with at least one piston and at least one displacerco-operating with the former, while the connection between each of thecranks and the pistons and displacers respectively includes a pistonconnecting rod and a displacer connecting rod respectively. Therectilinearly moving parts of the piston connecting rods being locatedon one side and the rectilinearly moving parts of the displacerconnecting rods being located on the other side of the plane goingthrough the center lines of the crank shafts.

The term hot gas reciprocating engine as used herein not only denoteshot-gas engines but also cold-gas refrigerators and heat pumps,operating on the inverse hotgas engine principle.

In the known engines of the kind set forth, the synchronization of thetwo crank shafts is obtained by providing, on each of the crank shafts,a gear wheel so that the two gear wheels engage each other. One of thecrank shafts of such a machine is coupled with the driving or the drivenmachine, whereas the other crank shaft transfers its torque via the gearwheels to the other crank shaft. Apart from the synchronization the gearwheels are therefore used for the transfer of torque. Since the twocrank shafts will have unequal inertia moments and since the torquefluctuates, the tooth and bearing tolerances will have to meet verysevere requirements in view of the noise level. It will be obvious thatthe number of revolutions of the engine and that of the driving ordriven machine will, in general, differ from each other, so that acomparatively expensive reducing member is required between the crankshaft and the driving or the driven machine.

The invention has for its object to provide an improved structure of thehot-gas'reciprocating engine of the kind set forth and is characterizedin that the two crank shafts are connected with each other by theprovision of a worm and a worm wheel thereon, each of which engages aworm wheel and a worm respectively on a third shaft, which crosses thecrank shafts and which establishes a coupling between the hot-gasreciprocating engine and the driving or the driven machine.

An advantage of the construction according to the invention consists inthat the worm and worrn wheel transice mission is capable of providingnot only the synchronization of the numbers of revolution of the crankshafts, but also, with a suitable choice of the dimensions, a correcttransmission ratio between the number of revolutions of the hot-gasreciprocating engine and that of the driven or the driving machine. Theexpensive reducing gear required in the known construction between thecrank shaft and the driven or the driving machine is thus dispensable. Afurther advantage of the worm and worm wheel transmission is that sincesimultaneously a plurality of teeth of the worm wheel engage the wormsuch a transmission gear produces only little noise. This isparticularly favorable with hot-gas reciprocating engines whichthemselves operate substantially without noise or vibrations.

A further advantage of the hot-gas reciprocating engine according to theinvention resides in that the third shaft can occupy a position in whichit is parallel to the plane of the crank shafts. This is particularlyadvantageous in hot-gas reciprocating engines mounted in a ship inhorizontal position, in which case the driving gear is arranged so thatthe crank shafts are located one above the other and extendsubstantially parallel to the bottom of the vessel. Under certainconditions it may be desirable for the propulsion to employ a screwdriven by a vertical shaft. In accordance with the invention the thirdshaft can be directly employed to this end.

In a further advantageous embodiment of the hot-gas reciprocating engineaccording to the invention the third shaft intersects the plane goingthrough the crank shafts. The third shaft (output shaft) may then extendparallel to the center line of the cylinder, in contrast to knownstructures in which the output shaft crosses the center line of thecylinder at right angles. This may bring about a great advantage, forexample, if a hot-gas reciprocating engine has to be built in alow-roofed space, for instance below the bottom of a vessel inhorizontal position.

A further embodiment of the hot-gas reciprocating engine according tothe invention has the feature that each pair of piston connecting rodshas two pistons and each pair of displacer connecting rods has twodisplacers, said pistons and displacers being all located on the samecenter line, while the head faces of the pistons and displacers areremote from each other.

A further advantageous embodiment of the hot-gas reciprocating engineaccording to the invention is characterized in that the engine comprisesat least two pair or" associated cranks, each pair of cranks beingconnected with two pistons and two displacers, the pistons anddisplacers connected with one pair of cranks having a common centerline, the head faces of said pistons and displacers being remote fromeach other, the center line of the pistons and displacers connected withone pair of cranks being parallel to the center line of those connectedwith the other pair of cranks. In this way a very compact constructionof a four-cylinder hot-gas reciprocating engine is obtained the heightof which may be very small.

A further embodiment of the hot-gas reciprocating engine according tothe invention is characterized in that it comprises at least two pairsof crank shafts, the crank shafts of each pair being parallel to eachother and adapted to rotate in synchronism in opposite directions and inco-phase, while the pairs. of crank shafts are arranged in parallelplanes at a small distance from each other, so that the crank shafts ofone pair cross those of the other pair. Furthermore, each pair of crankshafts has at least two pairs of associated cranks and each pair ofcranks is connected with two pistons and two displacers, the head facesof said pistons and clisplacers being remote from each other, whilethose pistons and displacers which are connected with one pair of crankshave one common center line, all common center lines being parallel toeach other. The engine comprises a third shaft, which intersects theplanes going through the crank shafts and is provided with a widenedworm wheel or widened worm or a plurality of worm wheels or wormsrespectively, which co-operate with worms and worm wheels respectivelyon each of the crank shafts.

According to a further aspect of the invention a plurality of hot-gasreciprocating engines according to the invention are arranged in linewith the third shaft and around the latter in horizontal positions.

According to a further advantageous embodiment the hot-gas reciprocatingengine according to the invention comprises two coaxial third shafts,one of which is accommodated at least partly inside the other, the twoshafts being provided with one or more worm wheels and wormsrespectively, which cooperate with worms and worm wheels respectively onthe crank shafts of one or more of the hot-gas engines arranged aroundsaid shaft. This embodiment has the advantage that two output shafts areavailable which are capable of rotating with different speeds.

In a further embodiment according to the invention it is possible tochoose the angle of the pitch of the worms or the worm wheels on onethird shaft so that this shaft rotates in a direction opposite that ofthe other shaft. This may be of great advantage for propelling shipswhere the output shafts are provided with screws.

In a further advantageous embodiment of the hot-gas reciprocating engineaccording to the invention the third shaft intersects the plane(s) ofthe crank shafts at an angle deviating from 90 while said third shaft isprovided with two worm wheels and two worms or a widened worm wheel or awidened worm, which cooperate with worms or worm wheels respectively onthe crank shaft. This is favorable for a flat twin engine of thethermodynamic reciprocating type, in which the third shaft is notlocated in the plane going through the center lines of the twocylinders, but slightly beyond said plane. The distance between thecylinders may then be particularly small, which is advantageous with thespace to be occupied. A further advantage resides in that particularlyin ships the third shaft leading to the screw must always extendslightly downwards. is solved by arranging the engine itself at anangle. According to the invention the hot-gas reciprocating engine canthen be arranged normally in the horizontal position, while the outputshaft is at an angle to the horizontal plane.

In a hot-gas reciprocating engine the number of revolutions of theengine will usually be higher than that of the driven machine. For thisreason the crank shafts of a hot-gas reciprocating engine will usuallybe provided with worms, while the third shaft will be provided with aworm wheel. In contrast thereto, the number of revolutions of a cold-gasrefrigerator will usually be lower than the number of revolutions of thedriving machine. In these machines the third shaft will usually beprovided with a worm and the crank shafts will have worm wheels.

The invention will be described more fully with reference to thedrawing, in which a number of hot-gas reciprocating engines are shown byway of example.

FIGS. 1, 2 and 3 are three cross sections of a hot-gas reciprocatingengine.

FIGS. 4 and 5 show diagrammatically a four-cylinder hot-gas engine, theformer in cross-section and the latter in elevation.

FIG. 6 shows diagrammatically an advantageous arrangement of aneight-cylinder hot-gas engine.

With known engines this diificulty I FIGS. 7 and 8 show aneight-cylinder hot-gas engine in which the cylinders are arranged aroundthe output shaft.

FIGS. 9 and 10 show a two-cylinder hot-gas engine in which the outputshaft is parallel to the plane going through the crank shafts.

Referring to FIGS. 1, 2 and 3 reference numeral 1 designates a cylinder,in which a displacer 2 and a piston 3 are adapted to reciprocate withphase difference. The piston 3 varies, during its displacement, thevolume of a compression space 4 and the displacer varies with its headface the volume of an expansion space 5. The compression space 4 and theexpansion space 5 communicate with each other through a cooler 6, aregenerator 7 and a heater 8. Heat is supplied to the head of thecylinder 1 and the heater 8 through a burner 9. The piston 3 isconnected through a piston rod 10 with a yoke 11. The displacer 2 isconnected through a displacer rod 12 with a yoke 13. The yoke 11 isconnected via piston connecting rods 14 with the cranks 15 of the crankshafts 16. The yoke 13 is connected through displacer connecting rods 17also with the cranks 15. The crank shafts 16 are provided with worms 18,which cooperate with a worm wheel 19 on a third shaft 20. The thirdshaft 20 is coupled with a shaft 21 of a driven machine 22. In operationthe torque of the crank shafts 16 will be trans ferred through the worms18 to the worm wheel 19 and hence to the output shaft 20. It will beobvious that the worms 18 and the worm wheel 19 have a double functioni.e. the synchronization of the crank shafts 16 and the transfer oftorque from the crank shafts 16 to the driven shaft 20.

From the drawing it will furthermore be seen that the number ofrevolutions of the crank shafts 16 is higher than that of the drivenmachine 22. This reduction of the number of revolutions is achievedwithout the need for a comparatively expensive reduction gear. Thedesired transmission ratio in this hot-gas engine is obtained by acorrect choice of the cooperating worms 18 and the worm wheel 19.

An advantage of this hot-gas engine is that the center line of thecylinder 1 and that of the driven machine are parallel to each other, sothat a horizontal hot-gas engine may be constructed with a very smallheight. This is important for example in ships, Where the engine may beaccommodated below the floor.

FIGS. 4 and 5 show diagrammatically a four-cylinder hot-gas engine. Thecylinders are designated by 31, 32, 33 and 34. The continuous crankshafts 35 are provided with worms 36, which cooperate with the wormwheel 37. The worm wheel 37 occupies an oblique position and is widened,so that the output shaft 38 is at an angle to the plane going throughthe center lines of the cylinders. The resultant construction is ahot-gas engine which also has a very low structural height and which isparticularly suitable for being accommodated below the floor of a vesselor water craft. A further advantage of this construction is that theshaft 38 is at an angle to the plane going through the cylinders. Thecylinders 31 and 32 may therefore have a smaller distance between theircenter lines than in the case in which the shaft 38 is located in theplane of these cylinders.

A further advantage is that the shaft 38 can be directly coupled with amachine located slightly outside the plane going through the centerlines of the cylinders. This may be the case in ships in which theengine is located at a higher level than the screw. According to theinvention it is now possible to couple the engine directly with thescrew through the shaft 38, without the need for an oblique position ofthe engine. It will be obvious that the crank shafts 35 may be extendedat will on both sides and may be provided with cranks. The engine maythus be extended on either side and further pairs of cylinders, so thateight or twelve cylinder hot-gas engines are obtained. FIG. 6 showsdiagrammatically the possibility of providing a third shaft 40 with forexample two worm wheels 41 and 42, with which worms 43 and 44 cooperate,arranged on crank shafts 45 and 46 respectively. These crank shafts 45and 46 are provided with cranks forming part of rhombic driving gears ofhot-gas engines. This provides an arrangement which is particularlysuitable for accommodation in a low-roofed, narrow space.

FIGS. 7 and 8 show a hot-gas engine having two output shafts 50 and 51.The shaft 50 is accommodated for the major part inside the .hollow shaft51. The two shafts 50 and 51 are provided with worm wheels 52 and 53respectively, with which co-operate the worms 54 and 55 respectively.The worms 54 are provided on the crank shaft 56 forming part of thedriving gears of the hot-gas engine cylinders 57 and 58. The worms 55are arranged on the crank shafts 59, which form part of the drivinggears of the hot-gas engine cylinders 60 and 61. The pitch angle of theworms 54 may be chosen so with respect to the pitch angle of the worms55 that the shafts 50 and 51 rotate in the same directions. The wormscon cerned may, however, also be chosen so that the shafts 50 and 51rotate in opposite directions, which may be important for the propulsionof ships. From FIG. 8 it will be seen that the cylinders 57, 58 and 60,61 are arranged symmetrically around the center of the engine. In thismanner a very compact construction of the hot-gas engine is obtained,which is extremely suitable for accommodation in a cylindrical,elongated space.

FIGS. 9 and show two cylinders 90 and 91 of a hotgas engine. In each ofthese cylinders the pistons 92 and displacers 93 are capable ofreciprocating with phase difference. During the movement of said membersthe volumes of a compression space 94 and of the expansion space 95 arevaried. Said spaces communicate with each other through a cooler 96, aregenerator 97 and a heater 98. Each of the pistons and displacers isconnected through a piston rod 100 and a displacer rod 101 respectivelywith a rhombic driving gear.

This rhombic driving gear comprises the yokes 103 and 104 with which thepistons and displacers respectively may be coupled. The yokes 103 and104 are connected in turn by connecting rods 105 and 106 respectivelywith cranks of the crank shafts 107. The crank shafts 107 are providedwith worms 108, which co-operate with worm wheels 109 on a third shaft110. The third shaft 110 is coupled through gear wheels 113 with themachine to be driven. In the drawing the driven machine is formed by thescrew 112, journalled in a housing 114, which may be rotatably connectedwith the ships floor.

In the operation of the hot-gas engine shown the piston and displacermovements are transferred through the yokes 103 and 104 respectively andconnecting rods 105 and 106 respectively to the crank shafts 107 and themovement of the crank shafts is transferred through the worms 108 andthe worm wheels 109 to the output shaft 110. This provides an extremelysimple coupling between the crank shafts and the output shaft and bysuitable choice of the worms and the worm wheels the correcttransmission ratio is obtained. The worms and worm wheels ensurefurthermore that the crank shafts rotate in synchronism and in oppositedirections. It should be noted here, that, since the crank shafts rotatein opposite directions, the pitches of the two worms or of the two wormwheels must be opposite each other. Although in the embodiment the twoworm wheels and worms have equal diameters, one worm wheel may have alarger diameter than the other, so that the worm co-operating with theworm wheel of larger diameter must have a smaller diameter than theother worm. The shaft 110 will then occupy a slightly oblique position.

As is shown in the drawing, the hot-gas engine according to theinvention is particularly suitable for accommodation in a low-roofedspace, for example below the floor of a ship.

Although the drawing shows only hot-gas engines, it will be obvious thata worm and worm wheel transmission may also be effectively used incold-gas refrigerators of the displacer type. In this case the thirdshaft will usually have a worm, while the crank shafts are provided withworm wheels, so that the driven machine has a higher speed than thecold-gas refrigerator.

What is claimed is:

1. A hot-gas reciprocating engine adapted for driving a driven elementcomprising; at least one cylinder, at least one piston and at least onedisplace-r adapted for reciprocation in said cylinder with a relativephase difference, at least one pair of identical cranks, at least twocrankshafts, said cranks being located each on one side of a planeextending through the center line of said engine and forming part ofsaid two crankshafts, said crankshafts being rotated in the same phase,in synchronism and in relatively opposite directions, the center linesof said shafts being parallel to each other and being locatedsymmetrically, each on one side of the plane going through said enginein a plane at right angles to the center line of said engine, each pairof associated cranks being connected with at least one piston and atleast one displacer, at least one piston connecting rod connecting saidpiston and the respective crank, at least one displacer connecting rodconnecting said displacer and the respective crank, the rectilinearlymoving parts of said piston connecting rods being located on one sideand the rectilinearly moving parts of the displacer piston being locatedon the other side of the plane extending through the center lines ofsaid crank shafts, a worm mounted on each of said crank shafts, andanother shaft provided with a worm gear which couples said hot-gasreciprocating engine with said driven element.

2. A hot-gas reciprocating engine as claimed in claim 1 wherein saidother shaft is at least substantially parallel to the plane extendingthrough said crank shafts.

3. A hot-gas reciprocating engine as claimed in claim 1 wherein saidother shaft intersects the plane extending through said crank shafts.

4. A hot-gas reciprocating engine as claimed in claim 1 wherein eachpair of piston connecting rods is connected to two pistons and each pairof displacer connecting rods is connected to two displacers, saidpistons and displacers having a common center line, and the headsurfaces of said pistons and displacers being remote from each other.

5. A hot-gas reciprocating engine as claimed in claim 1 wherein saidengine comprises at least two pairs of associated cranks, each pair ofcranks being connected with two pistons and two displacers respectively,the pistons and displacers connected with one pair of cranks having acommon center-line, and the center line of said pistons and displacersconnected with one pair of cranks being parallel to the center line ofsaid pistons and displacers connected with the other pair of saidcranks.

6. A hot-gas reciprocating engine as claimed in claim 1 wherein saidengine comprises at least two pairs of crankshafts, the crankshafts ofeach pair being parallel to each other and rotating in synchronism, inco-phase and in opposite directions, the pairs of crankshafts beingarranged in parallel planes spaced apart by a relatively small distanceso that one pair of crankshafts cross the other pair of crankshafts,each pair of crankshafts comprising at least two pairs of associatedcranks, and each pair of cranks being connected with two pistons and twodisplacers.

7. A hot-gas reciprocating engine as claimed in claim 6 wherein saidengine is provided with said other shaft around which a plurality ofengines are arranged parallel to the longitudinal axis of said othershaft.

8. A hot-gas reciprocating engine as claimed in claim 7 wherein saidengine is provided with two co-axial other shafts, one of said shaftsbeing located at least partly inside the remaining shaft, said two othershafts being provided with at least one worm, and a worm gear connectedto each of said engines.

9. A hot-gas reciprocating engine as claimed in claim 8 wherein saidworms on at least one of said other shafts has such an angle of pitchrelative to said worm on the remaining other shaft that in operation thesaid two other shafts rotate in opposite directions.

10. A hot-gas reciprocating engine as claimed in claim 1 wherein saidother shaft intersects the plane exteiyling through the crankshafts atan angle less than 90, said other shaft being provided with at least oneworm gear, and a worm connected to each of said crankshafts, said wormsco-acting with said worm gear.

11. A hot-gas reciprocating engine as claimed in claim 10 wherein saidother shaft is at an angle of not more than 15 to the plane extendingthrough the center lines of said piston and displacer.

References Cited by the Examiner FOREIGN PATENTS EDGAR W. GEOGHEGAN,Primary Examiner.

1. A HOT-GAS RECIPROCATING ENGINE ADAPTED FOR DRIVING A DRIVEN ELEMENTCOMPRISING; AT LEAST ONE CYLINDER, AT LEAST ONE PISTON AND AT LEAST ONEDISPLACER ADAPTED FOR RECIPROCATION IN SAID CYLINDER WITH A RELATIVEPHASE DIFFERENCE, AT LEAST ONE PAIR OF IDENTICAL CRANKS, AT LEAST TWOCRANKSHAFTS, SAID CRANKS BEING LOCATED EACH ON ONE SIDE OF A PLANEEXTENDING THROUGH THE CENTER LINE OF SAID ENGINE AND FORMING PART OFSAID TWO CRANKSHAFTS, SAID CRANKSHAFTS BEING ROTATED IN THE SAME PHASE,IN SYNCHRONISM AND IN RELATIVELY OPPOSITE DIRECTIONS, THE CENTER LINESOF SAID SHAFTS BEING PARALLEL TO EACH OTHER AND BEING LOCATEDSYMMETRICALLY, EACH ON ONE SIDE OF THE PLANE GOING THROUGH SAID ENGINEIN A PLANE AT RIGHT ANGLES TO THE CENTER LINE OF SAID ENGINE, EACH PAIROF ASSOCIATED CRANKS BEING CONNECTED WITH AT LEAST ONE PISTON AND ATLEAST ONE DISPLACER, AT LEAST ONE PISTON CONNECTING ROD CONNECTING SAIDPISTON AND THE RESPECTIVE CRANK, AT LEAST ONE DISPLACER CONNECTING RODCONNECTING SAID DISPLACER AND THE RESPECTIVE CRANK THE RECTILINEARLYMOVING PARTS OF SAID PISTON CONNECTING RODS BEING LOCATED ON ONE SIDEAND THE RECTILINEARLY MOVING PARTS OF THE DISPLACER PISTON BEING LOCATEDON THE OTHER SIDE OF THE PLANE EXTENDING THROUGH THE CENTER LINES OFSAID CRANK SHAFTS, A WORM MOUNTED ON EACH OF SAID CRANKSHAFTS, ANDANOTHER SHAFT PROVIDED WITH A WORM GEAR WHICH COUPLES SAID HOT-GASRECIPROCATING ENGINE WITH SAID DRIVEN ELEMENT.